CALGARY, Alberta - A veterinarian called for safer standards for the transport of large animals after the accidental death of a hippopotamus in Calgary, Alberta, a report said.

Hazina, a 6-year-old river hippo, died in of a heart attack in Calgary just two days after her departure from the Denver Zoo, the Calgary Herald reported Tuesday.

Reports said the hippo may have suffered circulatory problems as a result of laying on one side of her body for as long as 11 hours during the 29-hour trip from Denver.

Dr. Jacques Dancosse of the Animal Care Team of the International Air Transport Association said mandatory stops and non-slip floors should be required while large animals are being moved so they can stand up and alternate laying on both sides of their bodies.

The call for new animal travel regulations came three months after Hazina's death last fall. The hippo was being moved to Canada to participate in a captive breeding program.